Seleção de genótipos de tomateiro submetidos ao estresse hídrico em função da expressão de características fisiológicas

Abstract

RESUMOObjetivou-se neste trabalho avaliar o comportamento fisiológico de diferentes genótipos de tomateiro, a fim de contribuir com a seleção de plantas com tolerância ao estresse hídrico. Utilizou-se o delineamento casualizado em blocos, com três blocos e dez tratamentos, sendo: oito genótipos F 2 RC 1 [UFU80-F 2 RC 1 #1 (3.5); UFU102-F 2 RC 1 #7 (13.4); UFU102-F 2 RC 1 #7 (13.3); UFU102-F 2 RC 1 #7 (16.8); UFU102-F 2 RC 1 #3 (2.7); UFU80-F 2 RC 1 #1 (11.8); UFU102-F 2 RC 1 #7 (16.7); UFU102-F 2 RC 1 #3 (14.5) ], e outros dois genótipos utilizados como testemunhas UFU-650 e LA-716. O experimento foi conduzido em ambiente protegido com monitoramento da densidade de fluxo (W m -2 ), radiação solar global (Qg), temperatura do ar (ºC), umidade relativa do ar (%) e o potencial mátrico no substrato (kPa). As características fisiológicas coletadas foram: temperatura foliar (T leaf ), CO 2 interno (Ci), transpiração (E), condutância estomática (gs) e assimilação de CO 2 (A), determinadas pelo analisador portátil de gás no infravermelho -IRGA. Pode-se observar que o acesso selvagem S. pennellii foi 6,96 vezes inferior em relação ao genitor recorrente UFU-650 (linhagem pré-comercial, susceptível ao déficit hídrico). A condutância estomática (gs) apresentou valores significativos entre os genótipos. Os resultados obtidos contribuem para caracterização fisiológica do acesso Solanum pennellii (tolerante a seca) e podem auxiliar na seleção de plantas F 2 RC 1 resistentes ao déficit hídrico. Palavras-chave: déficit hídrico, estresse abiótico, Solanum lycopersicum Selection of tomato genotypes under water stress due to the expression of physiological characteristics ABSTRACTThe objective of this study was to evaluate the physiological behavior of different tomato genotypes to assist in the selection of plants with tolerance to drought stress. It was used three blocks random and ten treatments: eight genotypes F 2 RC 1 [UFU80-F 2 RC 1 #1 (3.5); UFU102-F 2 RC 1 #7 (13.4); UFU102-F 2 RC 1 #7 (13.3); UFU102-F 2 RC 1 #7 (16.8); UFU102-F 2 RC 1 #3 (2.7); UFU80-F 2 RC 1 #1 (11.8); UFU102-F 2 RC 1 #7 (16.7); UFU102-F 2 RC 1 #3 (14.5)], UFU-650 and LA-716. The experiment was conducted in a greenhouse with monitoring the flux density (W m -2 ), solar radiation (Qg), air temperature (°C), relative humidity (%) and the matric potential in the substrate (kPa). The collected physiological characteristics were: leaf temperature (Tleaf), internal CO 2 (Ci), transpiration (E), stomatal conductance (gs) and CO 2 assimilation (A), determined by portable gas analyzer infrared -IRGA. It was observed that the wild tomato S. pennellii was 6.96 times lower than the recurrent parent UFU-650 (pre-commercial line, susceptible to drought). The stomatal conductance (gs) showed significant values among genotypes. The results contribute to physiological characterization access S. pennellii (drought tolerant) and can assist in the selection of F 2 RC 1 plants resistant to drought.

Genetic diversity and selection in tomato genotypes under water stress induced by mannitol

“…The pre-commercial line belongs to the germplasm bank of the UFU and it has determinate growth habit, large fruits (180 g) of Santa Cruz type and is susceptible to water stress. The wild access, LA-716, has indeterminate growth habit, small fruits (12 g) and is tolerant to water stress (ROUSSEAUX et al 2005, ROCHA et al 2016. After the F1 generation (hybrids) were obtained, the first and second backcrosses were made, in 2014 and 2015, respectively.…”

“…This fact can be explained for the lack of efficient methodologies that are used to select the genotypes (BERENGUER 2015). The wild access LA-716, S. pennellii, is originating from a dry and hot region and because of the evolution over time, the specie is efficiency on the water use, compared to the common cultivars (ROCHA et al 2016). Therefore, it is possible the introgression of genes, from S. pennellii, in advanced generations of tomato plants, aiming the development of genotypes that are tolerant to water stress.…”

Gas exchanges and water use efficiency in the selection of tomato genotypes tolerant to water stress

“…However, there are wild species that have a better water use efficiency than the commercial cultivars. The wild accession LA-716 (S. pennellii) is one of them and, although it does not present good agronomic characteristics, the wild species uses water more efficiently than the cultivated plants (Rocha et al, 2016). With the plant breeding, it is possible the rescue of important agronomic characteristics, through an interspecific cross followed by backcrossings with a background of interest (Maciel et al, 2011).…”

“…Direct methods, used for selection genotypes tolerant to water stress, are expensive and demand more time, which makes the indirect methods more viable. Many types of research have proven the efficiency of genotype selection from different techniques, like visual symptoms, soil water balance, the flow of sap, and gas exchange analyses (Aksic et al, 2011;Celebi, 2014;Begun et al, 2012;Rocha et al, 2016). However, the use of these techniques is scarce.…”

Déficit hídrico induzido por manitol para seleção de genótipos de tomateiro

“…Diante disso, aprimorar novas metodologias de seleção no melhoramento genético do tomateiro para tolerância à seca é de fundamental importância. Há relatos de métodos eficientes de seleção direta (Nahar & Ullah, 2006;Shamim et al, 2014;Rocha et al, 2016;Borba et al, 2017) e indireta em tomateiro (Aazami et al, 2010;Morales et al, 2015) visando avaliar a tolerância ao déficit hídrico, no entanto, tais procedimentos demandam maior período de tempo, custos elevados e exigem mais mão de obra para execução.…”